Underreamer



Patented sept. 1`, Y1925.

PATENT OFFICE.

K CHAR-LES L. ,DUNHALL oF rENNsBoRo, WEST'VIRGINIA. y

lUNDERREAMER.

' Application led Februa7 To all whom t may concern.'

.-*Beit known that I, CHARLES L. DUNHAM, a vcitizen of Vthe -United States, residing at Pennsboro, inthe countyY of Ritchie and State of West Virginia, have invented certain new .and useful Improvements in U11- derreamers; and Ido declare the following to be a full, clear, and exact descriptionA of the invention, vsuch as will enable others skilled in the art tol which it appertains to make and use ther same.

My invention relates to improvements in underreamers, used primarily in connection with well casings of oil wells, whenit is necessary to lower such casings. c .K

Vhile numerous underreamers have been heretofore devised and used,'they are open to 1certain'7objections. For instance, one wellknown type .of underreamer which relies .totally upon akey to retainall working parts within the body, often loses or breaks the key, so thatall working partsof the reamer fall to the bottom ofthe' 'well and cause almost endless trouble in fishing them out. In fact, very, often, the' wellV must be abandoned vand another VVdrilled adjacent thereto. Vhile other types of reamers have been used with some degree of success, they are complicated and expensive, andy they contain so many parts requiring milling or other machining, that thecost of manufacturel iis excessive. `l\f[oreover,V these complicateddevices are. liable to get out of order lil andcause a great deal of trouble.

It is the object of my invention to provide an `underreamer of extreme simplicity,

which may be manufactured at small cost,

yet' will be efficient, reliable, long-lived, and

Vin every way desirable. 40

With the foregoing-in View, the invention resides in vthe novel subject matter hereinafter v.described and claimed, the description being supplemented' by the accompanying drawings.y

Figure 1 is a vertical sectional View of an underreamer constructed in accordance with my invention, showing the relation of parts when theA deviceY isbeing either raised or lowered through a wellcasing.

Figure 2 is a duplicate of Fig. 1 with the exception ,that it illustrates the movable parts of the devicein position for operation of the reamer.

Figures 3 and 4 are transverse sectional 12, 1925. Serial No. 8,772.

views as indicated by lines 3 3 and 4-4 of Fig. 2.

Figure .5 is an inner side elevation of one of the cutters and its shank.

In the drawings above briefly described, l

the numeral 1 designates a vertically elongated body whose upper end is provided with the usual plug 2 for engagement with aV socket 3 or any means which may be used for operating the reamer. From its lower end, to a point a suitable distance above said end, the body l is formed with a cen-- tral longitudinal bore 4 which is of uniform diameter throughout its length, instead of f being of stepped form, as in certain other types of reamers.V 'By having the bore of this uniform diameter throughout its length, a great saving in time is eected during the Vmanufacture of the toolv and consequently a saving in cost is effected. Near its lower end, the body 1 is formed with a pair of opposedvertical slots 5, each of which extends throughout its entirety, from the interior to the exterior of the body. These slots f by which the shanks 9 are mounted in the L lower end ofthe bore 4. These shanks are integral with the upper ends of the cutters 6 f and they are pivotally mounted in a uniquemanner hereinafter described in de-r The Shanks 9 are provided with beveled upper ends 10 disposed between the slots 5, said slots receiving a pair of pivotally mounted dogs 12 having portions 13 pro-r` jecting into the bore 4 and normally lying againstthe beveled ends 10, as shown'in Fig. 1. dogs however, are formed with angular notches 14 which provide shoulders to engage the Shanks 9 and lock the cutters 6 in These projecting portions 13 of the the extended position shown in Fig. 2, movement of the dogs to the position of the last named figure, serving to project said cutters. For moving the dogs in this manner, a head 15 is sliduble in the upper portion of the bore el. and is forced normally in a downward direction by the action of a compression spring 17 which is confined between thc upper end of said bore and said head. Heretofore, whereas heads corresponding to the head .15 have commonly been slidably mounted in, bores and held in some manner against rotation, the construction of my invention is such that the aforesaid head 15 may be free to rotate in the bore, and may be of truly cylindrical form, so that it may be readily turned upon an ordinary lathe. The lower end of this head is formed with a shallow recess having an inwardly inclined, annular, cam surface 17 which engages the upwardly converging edges 1S of the dog portions 13, when the parts stand as shown in Fig. 1. By having the surface 17 of annular form, it will cooperate properly with the edges 1S, regardless of the position to which the head 15 may turn, it being` therefore unnecessary to provide any expensive means to hold this head against rotation.

`When the device is being lowered through a well casing, as shown in Fig. 1, the dogs 12 are within the contines of the body 1 and the cutters 6 are held in retracted position by contact of their enlargements 19 with thewell casing. As soon as the cutters G and dogs 12 have been lowered sufriciently to free the casing however, the head 15 is downwardly shifted by the spring 1G, and the co-acting cam surfaces 17 and 1S then swing the upper ends of the dogs 12 inwardly to the position shown in Fig. 2, and during this inward movement, the portions 123 of said dogs force the upper ends of the Shanks 9 together, thus spreading the cutters 6 to operative position. As soon as the cutters have reached this position, the notches 1-1- of the dogs 12 have snugly received the upper ends of the shanks V9, and as said dogs are held in this position by the spring-pressed head 15, they will positively lock the cutters in position for operation.

Upon withdrawal of the device from the well, the lower ends 20 of the dogs 12 strike the lower end of the casing and thus these dogs are rocked, so that the co-acting cani surfaces 17 and 1S will force the head 15 upwardly against the action of the spring 1G. This movement of the dogs also frees the upper ends of the shanks 9, so that when the enlargements 19 of the cutters 6 come in contact with the casing, said cutters mav move inwardly and readily enter said casing.

As above suggested, a unique pivotal mounting means for the shanks 9 has been shown, this mounting means being of such construction that it may be easily and inexpensively manufactured, will be exceptionally strong and durable in use, and will act to plug the lower end of the bore 4; against the entrance of an excessive amount of mud or other foreign matter. Each shank 9 is of substantially semi-conical form, and at its lower end, half the width of each shank is cut away by an ordinary planer or shaper to provide a recess 21 having straight, converging, upper and lower, edge walls 22 and a flat vertical side wall 23. Each shank 9 is provided at its lower portion with a laterally extending lug 211 having straight, converging, upper and lower edges 25 and a vertical side which is flush with or in the same plane with the side wall 23 of the recess 21. From the plane of the surface 23 to one vertical edo'e of each cutter 6, the latter is provided with a beveled rib 2G, and from said plane to the opposite vertical edge of the cutter, the latter is formed with a bevel 27.

The two shanks 9 and their lateral lugs 2-1 jointly f orm a substantially conical structure which plugs the lower end of the bore 4 as shown in the drawing, when the cutters are expanded for use, and it will be seen from Figs. 1 and 2 that the lug 24- of each shank is received in the recess 21 of the other shank, the flat vertical faces of said lugs and recesses being in Contact with each other. Moreover, it will be seen that the beveled rib 26 of each cutter 6 overlies the bevel 27 of the other cutter.

To mount the shanks in the bore 4., a pivot pin or screw 28 passes transversely through the lower end of the body 1 and passes also through the lugs 24. Then the reamer is in use, there is no strain upon this pivot, on account of the continuous knocking shoulders 8 which engage the lower ends of the body 1, substantially throughout the circumference of the latter. Thus, there is no danger of the pivot shearing and permitting the cutters to drop into the well. 1f either of the shanks should break and a cutter be lost, no other parts of the reainer may descend also and thus it is only necessary to fish for the lost cutter instead of for a multiplicity of parts as is very often necessary in connection with types of reamers now on the market.

Each cutter 6 and its integral shank 9, may be formed by drop forging, and the finishing` of these parts may be accomplished upon an ordinary lathe, and a shaper or planer, it being unnecessary to use any expensive milling machine work in the construction of the improved reamer.

Excellent results are obtainable from the details disclosed and they may therefore be followed. ITowever, within the scope of the invention as claimed, modifications may of course be made.

I claim: 1 l. An underreamer comprising va vertically elongated body having a central longitudinal bore which: opens throughY its lower end, said body also having a pair of opposed vertical slots near its lower end, a pair of cutters under thev body having shanks extending into the aforesaid bore and pivoted to said body, a pair of dogs pivotally mounted in the aforesaid slots and co-acting directly with the upper endsof said shanks to lock the cutters in expanded position, and a spring-lowered head slidable in the aforesaid bore over the dogs, said head being co-operable with Vsaid dogs to force the same to cutter-locking position when expansion of the cutters 'is permitted, and to hold said dogs in cutter-locking position while operating the reainer, said dogs having portions adapted to strike the lower end of a well casing to move them to cutterreleasing position and to raise the aforesaid head when the reamer is withdrawn from a well. Y

2. An underreamer comprising a vertically elongated body having a central longitudinal bore which opens through its lower end, said body also having a pair of opposed vertical slots near its lower end, a pair of cutters under the body having shanks extending into the aforesaid boreand pivoted to said body, a spring-lowered dogactuating and holding head slidable in said bore adjacent the upper `ends-of said slots, and a pair of dogs pivotally mounted in said slots and having portions interposed directly between and in contact with said head and said shanks, said dogs having abrupt shoulders adapted to engage said shanks and lock the'cutters in expanded position when said dogs are moved to operative position by said head, `the dogs being provided with other portions adapted to strike the lower end ofa well casing to move them to cutter-releasing position and to raise they aforesaid head when the reamer is withdrawn from a well.

3. An underrea-mer comprising a vertil cally elongated body having a central longitudinal bore which opensr through its lower end, said body also having a pair of opposed vertical slots near its' lower end, a pair of cutters under theV body having Shanks extending into the aforesaid bore and pivoted to said body, a pair of dogs pivotallyr mounted in theaforesaid slots and co-acting directly with the upper ends of said shanks to lock the cutters in expanded position, and a spring-lowered head slidable in the aforesaid bore over the dogs, said head having an annular cam surface engaging said dogs to move the latter to cutter-locking position when the cutters are permitted to expand regardless of the position to which axis, said dogs having portions adapted to strike the lower end of a well casing to move them to cutter-releasing position and to `opening. through its lower end, said body being also provided with a pair of opposed vertical slots near its lower end and extending intheir entirety from the exterior to theV interior of tliefbody, a pair of cutters adapted to abut the lower' end of the body and having Shanks which extend into the aforesaid bore and are pivoted to said body, said Shanks having upwardly beveled upper ends disposed Vbetween the aforesaid slots, a pair of flat cutter-locking dogs pivotedin said slots and having inwardly projecting portions to rest on said beveled ends of said shanks when the cutters are contracted, said inwardly projecting portions having angular notches to engage the cutter shanks and lock the same when the cutters are expanded and being also provided with upper ends which converge upwardly when the dogs yare in released position, a cylindrical dogactuating head slidable in the aforesaid bore andhaving a 4recess in itslower end provided with an inwardly inclined annular wall engaging said upwardly converging upper ends of said inwardly projecting dog n portions, and a coiled compression spring Vinterposed between the upper end of the aforesaid bore and said head and adapted to force the latter downwardly to move the dogs to cutter-locking position when expansion of the cutters is permitted, said dogs having portions adapted to strike the lower, end of a well casing to move them to cutterieleasing position and to raise the aforesaid head when the reamer isfwithdrawn from` a well. 1 v

5. An underreamer including a body having a bore which opens' through its lower end; a pair of cutters whose upper ends abut thev lower end of said body substantially throughout the circumference of the latter when said cutters are expanded; substantially semi-conical upstanding Shanks integral with the upper ends of said cutters and each having half its width out away near its lower end to provide a recess having straight converging upper and lower edge walls and a flat vertical side wall, each of said: Shanks being provided with an in` tegral lateral lug having upper and lower straight converging edges, said lug also having a flat inner vertical side in the same plane with said vertical side wall of the iecess; the lug of each shank being received in the recess of the other shank with the abovenamed fiat portions of the two Shanks in said head may have turned about a vertical contact; and a pivot pin passing transversely through the aforesaid body and through the lugs of said Shanks; Said Shanks and their lugs jointly plugging the lower end of the aforesaid bore against appreciable entrance of foreign matter.

6. A structure as specified in claim 5; each Cutter having a beveled rib at the upper end of its inner side from the flat side of its lug to one vertical edge of the cutter, each cutter having also a bevel from said flat side of its lug to its other vertical edge; the beveled rib of each Cutter overlying the bevel of the other cutter.

In testimony whereof I have hereunto affixed my signature.

CHARLES L. DUNHAM. 

